Sensitive carb

[R-4-L]

as usual I do several clicks of tuning wheneve I go out to fly..

using c-spec .91 OMI mods + viperhead dual..

yesterday the engine was doing fine only a little bit rich so I lowered it down and closed the mid-needle only 2 clicks. in doing that the engine ran really really lean! and almost no smoke coming out of muffler..

lowered it down after a scary engine bugg. opened 2 clicks, its rich again!

any thought?

[DavidH]

Well normally I don't have to tune the engine, unless the temps outside have changed 20 degs from last time I flew. My OS CSpec with OMI BB and Cline are consistent from one day to the next.
And it normally takes 5 or 6 clicks maybe more to go from nice running condition to a lean running condition. If 2 clicks is going from rich to lean. I would look for something in the carb.
Why did you lean just the mid range needle?

David

[R-4-L]

I lean the midrange to see my hovering tuning, so I hover and check my engine's performance and sound.. I keep tuning from day to day to experiment how my engine would perform and to find my optimum needle adjustment..

so I hovered, found that the engine is ok, but as usual lacking great amount of power when performing some maneuvers. and climbouts were not impressive either.. so I closed the mid a few clicks..

I found that the high-end needle adjustments do very little (or none) change.

[DavidH]

I found that the high-end needle adjustments do very little (or none) change.

The needle that the Cline regulator is attached is the high end needle. This needle affects the other needles. The needle that the Cline is attached controls the flow of fuel into the carb.

I fly the heli around doing aerobatics and keep the system loaded hard to check the mixture on the high end. If the mixture is OK on the high end. I then bring the heli in and hover it and check the mixture on the mid range. I adjust the mid range to give a nice consistent drone in a hover. I then fly around again do aerobatics, loading and unloading the engine. The engine should transistion back and forth between the high end and mid range consistently with little change.

David

[R-4-L]

I see, the midrange needle is there to prevent leaning out the engine when going from loading to hovering..

so I should focus on the high end adjustments while loading the engine, and then when finding a good mixture while under load, I go to hover and see my hovering mixture..

If I do that i'll probably end up with almost half a turn on high end but can feel safe as the mid-range would be rich enough not to over-rev the engine.. is that right david?